926 research outputs found
Elastocapillary folding of three dimensional micro-structures using water pumped through the wafer via a silicon nitride tube
In this paper we present the first investigation of a batch method for folding of threedimensional micrometer-sized silicon nitride structures by capillary forces. Silicon nitride tubes have been designed and fabricated using DRIE at the center of the planar origami patterns of the structures. Water is brought to the structures by pumping the liquid through the wafer via those tubes. Isolated micro-structures were successfully folded using this method. The potential of this technique for batch self-assembly is discussed
Capillary origami of micro-machined micro-objects: Bi-layer conductive hinges
Recently, we demonstrated controllable 3D self-folding by means of capillary
forces of silicon-nitride micro-objects made of rigid plates connected to each
other by flexible hinges [1]. In this paper, we introduce platinum electrodes
running from the substrate to the plates over these bendable hinges. The
fabrication yield is as high as (77 +/- 2) % for hinges with a length less than
75 {\mu}m. The yield reduces to (18 +/- 2) % when the length increases above
100 {\mu}m. Most of the failures in conductivity are due to degradation of the
platinum/chromium layer stack during the final plasma cleaning step. The
bi-layer hinges survive the capillary folding process, even for extremely small
bending radii of 5 {\mu}m, nor does the bending have any impact on the
conductivity. Stress in the different layers deforms the hinges, which does not
affect the conductivity. Once assembled, the conductive hinges can withstand a
current density of (1.6 +/- 0.4) A/cm . This introduction of
conductive electrodes to elastocapillary self-folded silicon-based
micro-objects extends the range of their possible applications by allowing an
electronic functionality of the folded parts.Comment: Currently on a peer review process. 13 page
Elastocapillary folding using stop-programmable hinges fabricated by 3D micro-machining
We show elasto-capillary folding of silicon nitride objects with accurate
folding angles between flaps of 70.60.1{\deg} and demonstrate the
feasibility of such accurate micro-assembly with a final folding angle of
90{\deg}. The folding angle is defined by stop-programmable hinges that are
fabricated starting from silicon molds employing accurate three-dimensional
corner lithography. This nano-patterning method exploits the conformal
deposition and the subsequent timed isotropic etching of a thin film in a 3D
shaped silicon template. The technique leaves a residue of the thin film in
sharp concave corners which can be used as an inversion mask in subsequent
steps. Hinges designed to stop the folding at 70.6{\deg} were fabricated
batchwise by machining the V-grooves obtained by KOH etching in (110) silicon
wafers; 90{\deg} stop-programmable hinges were obtained starting from silicon
molds obtained by dry etching on (100) wafers. The presented technique is
applicable to any folding angle and opens a new route towards creating
structures with increased complexity, which will ultimately lead to a novel
method for device fabrication.Comment: Submitted to a peer reviewed journa
Pour un échantillonnage et un conseil agronomique raisonné, les outils d'aide à la décision
To a sampling and personal fertility advice, the tools for decision support. Environmental and agronomic issues require always more well thought and suited farmer management of agricultural inputs; soil analysis is therefore an essential tool to support decision. However, for a soil analysis to provide valuable information, it is essential for the sample to be representative of the studied field. Without this representativeness, an analytical result, as accurate as it could be, would not be of interest if it could mislead the farmer. In practice, the main difficulty for the sampler is the recognition of soil criteria which are essential to provide a fertility advice, especially in Wallonia (Belgium) where soil variability is very important. With the Digital Soil Map of Wallonia (DSMW), drowned at the scale 1/5,000, it seems appropriate to give these information to the samplers in an useful form for routine works. That is why a mapping tool for decision support, named REQUACARTO, was designed to be used for soil analysis by provincial laboratories, members of the REQUASUD laboratories network. This tool responds to a real requirement in Wallonia: achieving a quality sampling for the development of personalized soil fertility advice
Isotopic and velocity distributions of Bi produced in charge-pickup reactions of 208Pb at 1 A GeV
Isotopically resolved cross sections and velocity distributions have been
measured in charge-pickup reactions of 1 A GeV 208Pb with proton, deuterium and
titanium target. The total and partial charge-pickup cross sections in the
reactions 208Pb + 1H and 208Pb + 2H are measured to be the same in the limits
of the error bars. A weak increase in the total charge-pickup cross section is
seen in the reaction of 208Pb with the titanium target. The measured velocity
distributions show different contributions - quasi-elastic scattering and
Delta-resonance excitation - to the charge-pickup production. Data on total and
partial charge-pickup cross sections from these three reactions are compared
with other existing data and also with model calculations based on the coupling
of different intra-nuclear cascade codes and an evaporation code.Comment: 20 pages, 12 figures, background information on
http://www-w2k.gsi.de/kschmidt
Measurement of nuclide cross-sections of spallation residues in 1 A GeV 238U + proton collisions
The production of heavy nuclides from the spallation-evaporation reaction of
238U induced by 1 GeV protons was studied in inverse kinematics. The
evaporation residues from tungsten to uranium were identified in-flight in mass
and atomic number. Their production cross-sections and their momentum
distributions were determined. The data are compared with empirical
systematics. A comparison with previous results from the spallation of 208Pb
and 197Au reveals the strong influence of fission in the spallation of 238U.Comment: 20 pages, 10 figures, background information at
http://www-wnt.gsi.de/kschmidt
Transition from participant to spectator fragmentation in Au+Au reaction between 60 AMeV and 150 AMeV
Using the quantum molecular dynamics approach, we analyze the results of the
recent INDRA Au+Au experiments at GSI in the energy range between 60 AMeV and
150 AMeV. It turns out that in this energy region the transition toward a
participant-spectator scenario takes place. The large Au+Au system displays in
the simulations as in the experiment simultaneously dynamical and statistical
behavior which we analyze in detail: The composition of fragments close to
midrapidity follows statistical laws and the system shows bi-modality, i.e. a
sudden transition between different fragmentation pattern as a function of the
centrality as expected for a phase transition. The fragment spectra at small
and large rapidities, on the other hand, are determined by dynamics and the
system as a whole does not come to equilibrium, an observation which is
confirmed by FOPI experiments for the same system.Comment: published versio
Pion radii in nonlocal chiral quark model
The electromagnetic radius of the charged pion and the transition radius of
the neutral pion are calculated in the framework of the nonlocal chiral quark
model. It is shown in this model that the contributions of vector mesons to the
pion radii are noticeably suppressed in comparison with a similar contribution
in the local Nambu--Jona-Lasinio model. The form-factor for the process
gamma*pi+pi- is calculated for the -1 GeV^2<q^2<1.6 GeV^2. Our results are in
satisfactory agreement with experimental data.Comment: 7 pages, 7 figure
Evaporation residues produced in spallation of 208Pb by protons at 500A MeV
The production cross sections of fragmentation-evaporation residues in the
reaction Pb+p at 500A MeV have been measured using the inverse-kinematics
method and the FRS spectrometer (GSI). Fragments were identified in nuclear
charge using ionisation chambers. The mass identification was performed
event-by-event using the B-rho - TOF - Delta-E technique. Although
partially-unresolved ionic charge states induced an ambiguity on the mass of
some heavy fragments, production rates could be obtained with a high accuracy
by systematically accounting for the polluting ionic charge states. The
contribution of multiple reactions in the target was subtracted using a new,
partly self-consistent code. The isobaric distributions are found to have a
shape very close to the one observed in experiments at higher energy. Kinematic
properties of the fragments were also measured. The total and the isotopic
cross sections, including charge-pickup cross sections, are in good agreement
with previous measurements. The data are discussed in the light of previous
spallation measurements, especially on lead at 1 GeV
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